What is the slope of a line perpendicular to the x-axis?
the slope of a line parallel to the
the slope of a line perpendicular to another will have a slope which is its negative reciprocal.
the negative reciprocal of a number is
the negative reciprocal of
this is undefined, since one cannot define the value of any number that is divided by
We say vertical lines have "no slope," horizontal lines have zero slope. The equation is
One may use a direction vector,